>>76347218 (OP)Aesthetically fat
Less superficially super skinny being underweight wrecks hell on your connective tissue and organ and glandular fuction to the point it may never recover entirely. Fat shits most just accelerate atherosclerosis and make themselves ugly permanently but we're really well equipped to treat the atherosclerosis and give them a more or less normal life expectancy.
The switch argument is cancer related but that's super specific to certain cancers. If you're guaranteed to get a certain cancer you're going to want to be like 30-40 lbs overweight so you don't die when they treat it. But it's less likely to grow in the first place (depending on what the cancer metabolizes with) if your so thin you're living in a metabolic depressed state.
Basically being a rail makes you immune to diabetes and most cancers but makes you more likely to die from everything else (which is still a huge amount of things) i think they both have similar averages but that's is not important for you specifically.